By Miles Evans

MELBOURNE, Mar 27 (Reuters) Natalie Coughlin tried an experimental approach to the world championships 100m backstroke final today and the result was an improvement on her own five-year-old world record.

The 24-year-old American, blasting away in lane six at Rod Laver Arena, surged clear of race favourite Laure Manaudou of France to touch home in 59.44secs and better her previous mark by 14 hundredths of a second.

Coughlin burst on to the international scene with her first world title in the event at Fukuoka, Japan in 2001, and a year later at the US championships she entered the record books by becoming the first women to break the minute mark.

She qualified fourth fastest for today's final and knew she had to try something different to upstage her rivals.

''You have to experiment to break world records and you learn from that experience,'' Coughlin, who completed the set of medals at the championships after her bronze in the 100m butterfly and silver in the 4x100 freestyle relay, told reporters.

''As soon as I got in the pool I went 100 percent and it took its toll in the last 10 metres but that's how you learn, I feel great now though.

''I'm really excited. I'm just really glad to get a best time, win gold. I just want to relax now and take it all in.'' Coughlin said the improvement this season had come from slight technical tweaks and extra attention to her body strength. ''It's all touchy feely stuff, trying to make everything one unit, trying to connect everything. I've been really working hard in the weight room the last year and a half and that's starting to pay off on my walls and turns.

''I especially felt great last week at training camp. I was pretty confident I could get a best time I'm glad I'm over it so now I can break it again.

''When I saw my time and didn't see the WR next to it, I was like 'What's going on?' because when they break a world or championship record they do that so I was just trying to do the math.'' REUTERS DH HT1720